Light Emitting Device, Electronic Equipment and Apparatus For Manufacturing the Same

ABSTRACT

To provide an aspect of a novel display device using a light emitting element which is composed of a cathode, an EL layer and an anode, and a manufacturing device of the display device. According to the present invention, dual-sided emission display can be performed in one sheet white color light emitting panel  1001  in which, for example, different images can be displayed on a topside screen and backside screen (full color display, monochrome display or area color display). Two polarizing plates  1002, 1003  are formed by shifting the position thereof with an angular deviation of 90 degrees each other so as to prevent outside light from passing through the pane, thereby realizing a black display when not displayed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light emitting device including alight emitting element in which phosphorescence or fluorescence can beobtained by applying an electric field to an element provided with afilm containing an organic compound (hereinafter referred to as an“organic compound layer”) between a pair of electrodes. The presentinvention further relates to a method of manufacturing thereof. In thisspecification, the light emitting device indicates an image displaydevice, a light emitting device, or a light source (including a lightingequipment). In addition, examples of the light emitting device alsoinclude a module with a connector such as a flexible printed circuit(FPC), a tape automated bonding (TAB) tape, and a tape carrier package(TCP) attached to a light emitting device, a module with a printedcircuit board provided at the end of a TAB tape or a TCP, and a modulewith an integrated circuit (IC) directly mounted on a light emittingelement by a chip on glass (COG) method. The present invention furtherrelates to a method of manufacturing the light emitting device.

2. Description of the Related Art

In recent years, researches on a light emitting device comprising an ELelement as a self-luminous light emitting element has been activated.The light emitting device is also referred to as an organic EL displayor an organic light emitting diode. The light emitting devices havecharacteristics such as high response speed which is suitable fordisplaying moving images, low voltage drive, and low power consumptiondrive. Therefore, the light emitting devices has recently beenattracting attention as a next-generation displays includingnew-generation cellular phones, personal digital assistants (PDA), andthe like.

The EL element includes a layer containing an organic compound in whichelectroluminescence can be obtained by applying electric field thereto,an anode, and a cathode. The electroluminescence in the organic compoundincludes light emission (fluorescence) upon returning form a singletexcited state to a ground state and light emission (phosphorescence)upon returning from the triplet excited state to the ground state.Either or both types of the luminescence can be used for the lightemitting device manufactured by a film formation device and a filmformation method according to the present invention.

As different from a liquid crystal display device, the light emittingdevice has characteristics in that they have no problem with the viewingangle because it is a self-luminous type. More specifically, the lightemitting device is more suitable for displays used in outdoors than theliquid crystal display. Various forms for use have been proposed.

In this specification, the light emitting element including the cathode,an EL layer and the anode is referred to as the EL element. The ELelement has two types: the system in which the EL layer is formedbetween two kinds of stripe electrodes disposed orthogonal to each other(simple matrix system), and the system in which the EL layer is formedbetween an opposite electrode and pixel electrodes connected to TFTs andarranged in matrix (active matrix system). However, when the pixeldensity is increased, the active matrix system in which a switch isprovided for each pixel (or a dot) is considered to be advantageousbecause it is available for low voltage drive as compared with thesimple matrix system.

Conventionally, there has been an electronic equipment in which aplurality of different panels is formed. For instance, a lap-topcomputer is provided with a monochromatic reflection type liquid crystalpanel for displaying simple display such as a power source level, and abattery level in addition to a main display screen panel (a transmissiontype liquid crystal panel for full-color display).

SUMMARY OF THE INVENTION

It is an object of the present invention to provide embodiment modes ofa novel display device using the light emitting element including thecathode, the EL layer, and the anode.

According to the present invention, the cathode and the anode are formedof transparent materials. A substrate and a sealing substrate arefurther formed of the transparent materials. With respect to the lightemission emitted from a layer containing an organic compound, dual-sidedemission display of light emission passing through the cathode and lightemission transmitting the anode can be simultaneously displayed.

The layer including the organic compound emit white color lightemission, and a color filter or a color conversion layer is formed suchthat one of the display screens performs full color display. The lightemitting direction which has ultimately large luminance may be selectedas that passing through the color filter. When an active matrix lightemitting device is used, the luminance is reduced by passing through aninterlayer insulating film or a protective film of a TFT. Therefore, itis preferable to form the color filter on the sealing substrate side inwhich the TFT is not formed.

According to the present invention, dual-sided emission display by onepanel (full-color display, monochrome display, and area color display)in which, for example, different images are simultaneously displayed,can be carried out.

By emitting white color light emission from the light emitting elementaccording to the present invention, it is possible to dispense with ahigh-precision metal mask used for selectively evaporating each minuteregion corresponding to R, G, and B, which leads to improvement ofproductivity. When the vapor deposition is selectively performed for R,G, and B, a large number of deposition chambers for R, G, and B arerequired. On the other hand, when white color light emission is used,the number of the evaporation chambers can be relatively reduced in themanufacturing device as compared with the vapor deposition for R, G, andB.

According to the present invention, two polarizing plates are providedin a panel by setting directions of the polarizing plates at rightangles, preventing outside light from transmitting through the panel. Asresult, a black display can be realized while the display is not carriedout on the panel. A circular polarizing plate used for preventing thereflection of light is formed of a special optical film and expensive.However, the polarizing plates used in this invention are versatilelyused in the field of liquid crystal panels and is inexpensive.

As shown in FIG. 1A, according to one aspect of the present invention,there is provided the light emitting device, including: a pixel portionhaving a plurality of light emitting elements which has a transparentfirst electrode, a layer containing an organic compound in contact witha surface of the first electrode, and a transparent second electrode incontact with a surface of the layer containing the organic compound; anda color filter, wherein the light emitting elements simultaneously emitblue-color light, phosphorescence from an organic metal complex, andlight from the organic metal complex in an excimer state so as togenerate white color light emission, wherein white color light emissionpassing through the second electrode generates full color displaythrough the color filter, and wherein white color light emission passingthrough the first electrode generates monochrome display.

As shown in FIG. 1B, according to another aspect of the presentinvention, there is provided the light emitting device, including: apixel portion having a plurality of light emitting elements each ofwhich has a transparent first electrode, a layer containing an organiccompound in contact with a surface of the first electrode, and atransparent second electrode in contact with a surface of the layercontaining the organic compound; a color filter; a first polarizingplate; and a second polarizing plate, wherein the light emittingelements simultaneously emit blue color light, phosphorescence from anorganic metal complex, and light from the organic metal complex in anexcimer state so as to generate white color light emission, whereinwhite color light emission passing through the second electrodegenerates full color display through the color filter and the firstpolarizing plate, and wherein white color light emission passing throughthe first electrode generates monochrome display through the secondpolarizing plate.

According to the aforementioned structures, the layer containing theorganic compound is characterized by comprising: a first light emittinglayer which emits blue color light; and a second light emitting layerwhich includes a phosphorescent material and simultaneously emitsphosphorescence from the phosphorescent material and the light emissionfrom the phosphorescent material in excimer state.

Further, according to the aforementioned structures, the second lightemitting layer is characterized in that a host material is mixed withthe phosphorescent material at a concentration of more than 10 wt % andless than 40 wt %, more preferably at a concentration of more than 12.5wt % and less than 20 wt %.

Generically, the host material contains less than 1 wt % of a singletcompound and 5 to 7 wt % of triplet compound. Therefore, each of thesinglet compound and the triplet compound are referred to as a dopantsince the concentration thereof is several wt %. According to thepresent invention, however, the concentration of the phosphorescentmaterial is more than 10 wt %, and therefore the phosphorescent materialis not the dopant. The concentration of the phosphorescent material isdifficult to be controlled at the several wt % as the dopant. In suchcases, when the amount of the phosphorescent material is minutelyvaried, radiation spectrum and electronic characteristics are easilychanged and varied. Meanwhile, according to the present invention, sincethe phosphorescent material is mixed at a concentration of not less than10 wt %, the concentration of the phosphorescent material is easilycontrolled, thereby a stable light emitting element can be obtained.

According to the aforementioned structures, the layer including theorganic compound is further characterized by including the three layersof: the first light emitting layer which emits blue color light; thesecond light emitting layer which includes the host material mixed withthe phosphorescent material, and simultaneously emits phosphorescencefrom the phosphorescent material and light from the phosphorescentmaterial in an excimer state; and an electron transporting layer.

According to the aforementioned structures, the first polarizing platesare characterized in that a polarizing axis of the first polarizingplate is shifted with an angular deviation of 90 degree from thepolarizing axis of the second polarizing plate. These polarizing plateshave advantageous effects of preventing appearance of the backgroundtransparently and reflection.

According to another aspect of the present invention, there is providedthe light emitting device, including: a pixel portion having a pluralityof light emitting elements each of which has a transparent firstelectrode, a layer containing an organic compound in contact with asurface of the first electrode, a transparent second electrode incontact with a surface of the layer containing the organic compound; afirst color filter; and a second color filter, wherein the lightemitting elements simultaneously emit blue color light, phosphorescencefrom an organic metal complex, and light from the organic metal complexin an excimer state so as to generate white color light emission,wherein white color light emission passing through the second electrodegenerates full color display through the first color filter includingcolored layers of three colors of red, blue and green, and wherein whitecolor light emission passing through the first electrode generatesmonochrome display through the second color filter which has one of thecolored layers of red, blue and green.

According to the aforementioned structures, the light emitting device isone of a video camera, a digital camera, a personal computer, or aportable information terminal.

According to another aspect of the present invention, there is provideda manufacturing apparatus, including: a loading chamber; a transportingchamber connected to the loading chamber; a plurality of film formationchambers connected to the transporting chamber; and an installationchamber connected to the film formation chambers, wherein the pluralityof film formation chambers is connected to a vacuum exhaust processingchamber for evacuating gas inside of each of the film formationchambers, and the plurality of film formation chambers including: ameans for fixing a substrate; an alignment means for aligning masks andthe substrate; one or two evaporation sources; a means for transportingthe evaporation source inside the film formation chambers and theinstallation chamber; and a means for heating the substrate, whereineach of the plurality of film formation chambers includes: a first filmformation chamber for forming a first light emitting layer which emitsblue color light by vapor deposition over an electrode formed over thesubstrate; a second film formation chamber for forming a second lightemitting layer which contains a phosphorescent material andsimultaneously emits phosphorescence from the phosphorescent materialand light in an excimer state by coevaporation; and a third filmformation chamber for forming an electron transporting layer over thesecond light emitting layer by vapor deposition.

In this specification, the excimer state indicates a state in a dimer(excitation dimer) which stably exists in an excitation state generatedby combining one molecule in a ground state and one molecule in anexcitation state which are of same kind.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A and 1B are views showing a dual-sided emission type lightemitting device (Embodiment Mode 1);

FIGS. 2A to 2C are views showing a dual-sided emission type lightemitting device (Embodiment Mode 1);

FIG. 3A is a top view and FIG. 3B is a cross sectional view showing astructure of an active matrix type EL display device (Embodiment 1);

FIGS. 4A to 4G are diagrams showing examples of electronic equipments(Embodiment 2);

FIG. 5 is a diagram showing a multi-chamber manufacturing device(Embodiment Mode 2);

FIG. 6 is a top view of an evaporation device (Embodiment 3);

FIGS. 7A to 7C are diagrams showing an installation chamber and a stateof transportation (Embodiment 3);

FIG. 8 is a cross sectional view of an evaporation apparatus (Embodiment4);

FIG. 9 is a top view of an interior of a film formation chamber(Embodiment 3);

FIG. 10 is a diagram showing radiation spectrum (Embodiment 5); and

FIG. 11 is a diagram showing a dependency of a radiation spectrum on anelectric current density (Embodiment 5).

DETAILED DESCRIPTION OF THE INVENTION Embodiment Modes

Embodiment modes according to the present invention will hereinafter beexplained.

Embodiment Mode 1

An example of a dual-sided emission type light emitting device accordingto the present invention will be described with reference to FIGS. 1Aand 1B and FIGS. 2A to 2C.

In FIG. 1A, a layer 1001 b containing TFTs as a switching element, and alayer 1001 c containing a light emitting element including an organiccompound, a cathode, and an anode are formed over a transparentsubstrate 1001 a. The substrate 1001 a and layers 1001 b and 1001 cconstitute a white color light emitting panel 1001. Note that protectivefilms, substrates and films for sealing are not illustrated in thedrawings for the sake of omitting additional explanations.

By attaching a color filter 1000 to the white color light emitting panel1001, a screen on one side can perform full color display.

FIG. 1B shows an example in which an optical film is used for thedual-sided emission type light emitting device in order not to displaybackground. Note that the same reference numerals are used for theidentical portions in FIGS. 1A and 1B.

FIG. 1A shows a cross sectional view of the light emitting device. Inorder to prevent outside light from passing through the light emittingpanel, the light emitting panel 1001 is sandwiched by polarizing plates1002 and 1003. By arranging the two polarizing plates so as to make thepolarizing directions of light orthogonal to each other, outside lightcan be blocked. Further, a light emitted from the light emitting panel1001 passes through only one polarizing plate, permitting display.

Therefore, portions other than emitting and displaying become black,which prevents background being seen from each side of the lightemitting device and also prevents display images from being hardlyrecognized for the viewers.

Although space is interposed between the polarizing plates 1002, 1003and the light emitting panel 1001, the present invention is not limitedto this configuration. The polarizing plates 1002, 1003 may be formed incontact with the light emitting panel 1001.

FIG. 2A is a cross sectional view showing a part of the pixel portion.FIG. 2B shows a schematic diagram for showing a lamination structure ina light emitting region. As shown in FIG. 2B, an EL layer can emit lightin both directions of the top surface and the bottom surface. Note that,a stripe alignment, a delta alignment, a mosaic alignment and the likecan be cited as the arrangement of the light emitting region, i.e., thearrangement of a pixel electrode.

In FIG. 2A, reference numeral 300 denotes a first substrate, referencenumerals 301 a and 301 b denote insulating layers, reference numeral 302denotes a TFT, reference numeral 318 denotes the first electrode (atransparent conductive layer), and reference numeral 309 denotes aninsulator. Reference numeral 310 denotes an EL layer, reference numeral311 denotes a second electrode, reference numeral 312 denotes atransparent protective layer, reference numeral 313 denotes a space,reference numeral 314 denotes the second substrate, reference numeral320 denotes a colored layer, and reference numeral 321 denotes a lightshielding layer.

The TFT 302 (p-channel TFT) formed over the first substrate 300 is anelement for controlling current flowing in the light emitting EL layer310, and reference numeral 304 denotes a drain region (or a sourceregion). Further, reference numeral 306 denotes a drain electrode (or asource electrode) that connects the first electrode and the drain region(or the source region). Further a wiring 307, such as an electric powersource line or a source wiring, is formed at the same time as the drainelectrode 306, using the same process. An example in which the firstelectrode and the drain electrode are formed separately is shown here,but they may also be formed at the same time. An insulating layer 301 athat becomes a base insulating film (a nitride insulating film as alower layer, and an oxide insulting film as an upper layer here) isformed over the first substrate 300, and a gate insulating film isformed between a gate electrode 305 and an active layer. Further,reference numeral 301 b denotes an interlayer insulating film containingan organic material or an inorganic material. Further, although notshown here, an additional TFT or a plurality of TFTs (n-channel TFT orp-channel TFT), may also be formed in one pixel. Furthermore, although aTFT having one channel forming region 303 is shown here, the presentinvention is not limited in particular to this, and a TFT having aplurality of channel forming regions may also be used.

Further, reference numeral 318 denotes the first electrode formed of thetransparent conductive film, that is, an anode (or a cathode) of an ELelement. Examples of the transparent conductive film include ITO (indiumtin oxide), indium oxide-zinc oxide (In₂O₃—ZnO), a zinc oxide (ZnO), andthe like.

Further, the insulator 309 (also referred to as a bank, a partitionwall, a barrier, an embankment, or the like) covers edge portions of thefirst electrode 318 (and the wiring 307). Inorganic materials (such assilicon oxide, silicon nitride, and silicon oxynitride), photosensitiveorganic materials and non-photosensitive organic materials (such aspolyimide, acrylic, polyamide, polyimide amide, resist, andbenzocyclobutene), laminates of these materials, and the like can beused as the insulator 309. A photosensitive organic resin covered with asilicon nitride film is used here. It is preferable to provide a curvedsurface having a radius of curvature only in an upper edge portion ofthe insulator when using a positive type photosensitive acrylic as theorganic resin material, for example. Further, negative typephotosensitive organic materials, which become insoluble in etchants byexposure to light, and positive type photosensitive organic materials,which become soluble in etchants by exposure to light, can be used asthe insulator.

Furthermore, a layer 310 containing an organic compound is formed byusing the vapor deposition or an application method. The layer 310containing the organic compound is formed by an evaporation apparatus soas to make a film thickness uniform. Note that, in order to improvereliability, the vacuum heat treatment (between 100° C. and 250° C.) ispreferably performed immediately before forming the layer 310 containingthe organic compound, thus performing degassing. For example, if thevapor deposition is used, evaporation is performed in a film formationchamber that has been vacuum-exhausted to a pressure equal to or lessthan 5×10⁻³ Torr (0.665 Pa), preferably between 10⁻⁶ and 10⁻⁴ Pa. Theorganic compound is gasified in advance by resistive heating in vapordeposition, and is dispersed toward the substrate by opening a shutterat the time of the vapor deposition. The gasified organic compound isdispersed upward, and is evaporated on the substrate after passingthrough an opening portion formed in a metal mask.

As shown in FIG. 2B, the EL layer (layer containing the organiccompound) 310 is composed by sequentially laminating a hole injectionlayer (HIL), a hole transporting layer (HTL), a light emitting layer(EML), an electron transporting layer (ETL), and an electron injectionlayer (EIL) from the anode side. CuPc as the HIL, α-NPD as the HTL, CBPincluding an organic metal complex in which platinum is used as acentral metal (Pt(ppy)acac) as the EML, bathocuproin (BCP) as the ETL,and BCP:Li as the EIL are typically used, respectively. White colorlight emission can be obtained in accordance with the lamination layerhaving above-described structure. Note that, the CBP is an abbreviationof 4,4′-N,N′-dicarbazole-biphenyl.

As the EL layer 310, a thin film formed of light emitting materials(singlet compound) which emit light (fluorescence) by a singletexcitation and a thin film formed of light emitting materials (tripletcompound) which emit light (phosphorescence) by a triplet excitation canbe employed.

The EL layer 310 has following characteristics. According to the presentinvention, white color light emission can be obtained with a simplelamination structure by utilizing the organic metal complex which usesplatinum as the central metal. The white light emission can be furtherobtained by using at least a first light emitting layer that emits bluecolor light and a second light emitting layer that simultaneously emitsphosphorescence and excimer light emission.

As the first light emitting layer that emits blue color light, a layercomposed of a single substance (blue-color light emitter) or a layerformed by dispersing (or mixing) a guest material which is blue-colorlight emitter to the host material can be employed.

Excimer emission is appeared in a region having a longer wavelength(more specifically, having a longer wavelength by no less than severaldozen nm) as compared to normal light emission (phosphorescence if thephosphorescent material is used). Therefore, excimer emission of thephosphorescence material that generates phosphorescence in a green colorregion appears in a red color region. Accordingly, peaks in therespective wavelength regions of red color, green color and blue colorcan be obtained by the excimer emission, and therefore a white-colororganic light emitting element with high-efficiency can be achieved.

As the specific example, for instance, there is a method in which thephosphorescent material having excellent planarity as a platinum complexis used as the guest material, and the concentration of thephosphorescent material is increased (more specifically, not less than10 wt %). By mixing the phosphorescent material at a high concentrationof not less than 10 wt % with the host material, the interaction betweenmolecules or polymer thereof of the phosphorescent material isincreased, which results in the derivation of the excimer emission. Inaddition, there is another method in which the phosphorescence materialis used as a thin film light emitting layer or a dot light emittingregion rather than using the phosphorescent material as the guestmaterial. Note that the method for leading out the excimer emission isnot limited thereto.

FIG. 2C is an example showing a simplest lamination structure. In thisexample, a HTL (α-NPD: film thickness of 30 nm), and an EML (CBPcontaining Pt(ppy)acac: film thickness of 30 nm), and an ETL (BCP: filmthickness of 20 nm) are sequentially laminated from the anode side. Thetriplet compound represented by Pt(ppy)acac has a high light-emittingeffeciency, and is effective in a large-sized panel. As illustrated inFIG. 2C, the EL layer is formed by laminating three layers, whichresults in reduction of the processing time. Further, increase in thenumber of the evaporation chambers for the manufacturing device can besuppressed, which is preferable for mass production. Furthermore, eachlayer is a thin film with a thickness of between 20 nm and 30 nm, andthin film is superior in material costs.

Further, reference numeral 311 denotes the second electrode made of aconductive film, that is, a cathode (or anode) of the light emittingelement. Alloy such as MgAg, MgIn, AlLi, inorganic materials such asCaF₂, and CaN, or a transparent film containing aluminum with an elementincluded in Group I or Group II of the periodic table by coevaporation,may be used as the material for the second electrode 311. The dual-sidedemission type light emitting device emits light by passing light throughthe second electrode is manufactured here, and therefore a 1 nm to 10 nmthick aluminum film, or a MgAg alloy film is used. If an Ag film isemployed as the second electrode 311, it becomes possible to form amaterial over the layer 310 containing the organic compound by using amaterial other than an oxide and the reliability of the light emittingdevice can be enhanced. Further, a transparent layer (film thickness 1nm to 5 nm) containing CaF₂, MgF₂, or BaF₂ may also be formed as acathode buffer layer before forming the Ag film with the thickness of 1nm to 10 nm.

In order to lower the resistance of the cathode, the transparentconductive film (such as an ITO (indium tin oxide) film, an indiumoxide-zinc oxide (In₂O₃—ZnO) film, or a zinc oxide (ZnO) film) may beformed to a thickness of between 50 nm and 200 nm. In order to lower theresistance of the cathode, an auxiliary electrode may also be formedover the second electrode 311 in a region which does not emit light. Thecathode may be evaporated by resistive heating and selectively formed byusing the evaporation mask.

Reference numeral 312 denotes a transparent conductive layer formed bysputtering or vapor deposition. The transparent conductive layer servesas a sealing film for protecting the second electrode 311 made of a thinmetal film and preventing penetration of moisture. As depicted in FIG.2B, a silicon nitride film, silicon oxide film, a silicon oxynitridefilm (SiNO film (a composition ratio of N>O) or SiON film (a compositionratio of N<O)), or a thin film containing carbon as its main component(for example, DLC film and CN film) obtained by sputtering or CVD can beused for forming the transparent conductive layer 312.

The transparent conductive layer 312 thus obtained is optimal for thesealing film of the light emitting element in which the layer containingthe organic compound is used as the light emitting layer.

The second substrate 314 and the first substrate 300 are bonded by asealing material (not shown). The sealing material includes a gapmaterial for securing a space between the substrates, and is arranged soas to surround the pixel region. The space 313 is filled with an inertgas, and a desiccant (not shown) is attached to the second substrate314. Further, the space 313 may be filled with a transparent sealingmaterial. In this case, UV curing epoxy resin or thermosetting epoxyresin can be used. The transparent sealing material is filled betweenthe pair of substrates, which enhances the entire transmittance ascompared with the case in which the gap between the pair of substrate isa space (inert gas).

Further, a color filter is attached to the second substrate 314according to the arrangement of the light emitting regions. The colorfilter includes colored layers 320 corresponding to red color (R), greencolor (G), and blue color (B), a light shielding layer 321 for shieldinglight between the colored layers, and an overcoat layer (notillustrated). Although Embodiment Mode 1 shows an example in which thecolor filter is attached to the outside surface of the second substrate314, the color filter may be attached to the inside surface. In thiscase, white color light emission passes through the second substrateafter passing through the color filter.

According to the present invention, it is possible to achieve a novelmode of light emitting display device in which one sheet panel comprisestwo display screens, and one of white color light emission passingthrough the anode and white color light emission passing through thecathode is displayed in full color and the other is displayed inmonochrome.

Embodiment Mode 2

FIG. 5 shows a top view of a multi-chamber type manufacturing device. Inthe manufacturing device as depicted in FIG. 5, chambers are arrangedfor the purpose of enhancing its production efficiency.

In the manufacturing device as depicted in FIG. 5, at least transportingchambers 502, 508 and 514 are always maintained in vacuum, and filmformation chambers 506W1, 506W2, and 506W3 are always maintained invacuum. Accordingly, a vacuum exhaust operation within the filmformation chambers and nitrogen filing operation within the filmformation chambers can be omitted, and therefore film formationtreatment can be subjected in succession at short times.

In one film formation chamber, only one layer in the EL layers includinglayers formed of different materials (such as a hole transporting layer,a hole injection layer, a light emitting layer, an electron transportinglayer, and an electron injection layer) is formed. Movable evaporationsource holders are installed within each of the film formation chambers.In each film formation chamber, a plurality of such evaporation sourceholders are prepared and appropriately provided with a plurality ofcontainer (crucibles) which have been filled with an EL material inadvance. A substrate is set in a face down manner, a position alignmentof an evaporation mask is performed by CCD or the like. Then, filmformation can be selectively performed by executing vapor deposition bymeans of resistive heating.

Installation of the containers (crucibles) encapsulated with the ELmaterial or component replacement of the evaporation source holders iscarried out in installation chambers 526 p, 526 q, 526 r, and 526 s. TheEL material has previously been put in the containers (crucibles as atypical example) by a material manufacturer. Namely, such setting ispreferably executed without exposing the EL material to the air;therefore, it is preferable that, when crucible is delivered from thematerial manufacturer, the crucible is put in a second container in asealed manner and then introduced into the film formation chamber as itis. Desirably, each of installation chambers is allowed to be in avacuum state, and under these circumstances the crucible is taken out ofthe second container in any one of the installation chambers to set thecrucible in any one of the evaporation source holders. In such manner,not only the crucible but also the EL material put in the crucible isprevented from being contaminated.

According to the present invention, the white color light emittingelement is realized by laminating the three layers containing theorganic compound. Therefore, the layers containing the organic compoundmay be formed by using at least three chambers. By using three chambers,processing time can be reduced, which further reduces cost for themanufacturing device. In addition, each layer may be a thin film with afilm thickness of 20 nm to 40 nm, which is superior in material cost.

In case of forming the white color light emitting element, for instance,a hole transporting layer (HTL), which also becomes the first lightemitting layer is formed in the film formation chamber 506W1, the secondlight emitting layer is formed in the film formation chamber 506W2, anelectron transporting layer (ETL) is formed in the film formationchamber 506W3, and then a cathode may be formed in the film formationchamber 510. A blue color fluorescent material having a holetransporting property such as TPD, and α-NPD may be used as a lightemitter in the first light emitting layer. Further, the organic metalcomplex using platinum as its central material is effective for thelight emitter in the second light emitting layer. More specifically,when substances as described in the following chemical formulas (1) to(4) are mixed with the host material at a high concentration (between 10wt % and 40 wt %, more preferably, between 12.5 wt % and 20 wt %), thesecond light emitting layer can emit phosphorescent emission and excimeremission. Note that present invention is not limited to the materials,and any material can be used as long as the material is a phosphorescentmaterial that simultaneously emits phosphorescent emission and excimeremission.

Examples of the electron transporting material that can be used for theelectron transporting layer (ETL) include: metal complexes such astris(8-quinolinolato)aluminum (abbreviated as Alq₃),tris(4-methyl-8-quinolinolato)aluminum (abbreviated as Almq₃), andbis(10-hydroxybenzo[h]-quinolinate)beryllium (abbreviated as BeBq₂),bis(2-methyl-8-quinolinolato)-(4-hydroxy-biphenyly)-aluminum(abbreviated as BAlq), bis[2-(2-hydroxypheyl)-benzoxazolato]zinc(abbreviated as Zn(BOX)₂), andbis[2-(2-hydroxypheyl)-benzothiazolato]zinc (abbreviated as Zn(BTZ)₂).Other materials that are capable of transporting electrons than themetal complexes include: oxadiazole derivatives such as2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviated asPBD) and 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene(abbreviated as OXD-7); triazole derivatives such as3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole(abbreviated as TAZ) and3-(4-tert-butylphenyl)-4-(4-ethylpheyl)-5-(4-biphenylyl)-1,2,4-triazole(abbreviated as p-EtTAZ); imidazole derivatives such as2,2′,2″-(1,3,5-benzenetrile)tris-[1-phenyl-1H-benzimidazole](abbreviated as TPBI); and phenanthroline derivatives such asbathophenanthroline (abbreviated as BPhen) and bathocuproin (abbreviatedas BCP).

Particularly, the second light emitting layer may be formed by mixingone kind of metal complex with the host material at a high concentration(between 10 wt % and 40 wt %, more preferably, between 12.5 wt % and 20wt %) by means of coevaporation, permitting easy control of theconcentration thereof. Therefore, the second light emitting layer issuitable for mass production.

A region other than the portion in which a leading electrode is exposed(where will subsequently be attached with a FPC) is simply masked withan evaporation mask.

In order to form a dual-sided light emitting panel, the cathode isformed by laminating a thin metal film and transparent conductive film.The thin metal film (Ag or MgAg) is formed to a thickness of between 1nm and 10 nm by resistive heating, whereas the transparent conductivefilm is formed by sputtering. Therefore, the cathode is formed at shorttimes.

In Embodiment Mode 2, an example of manufacturing the white color lightemitting panel is shown. However, it is also possible to form anothermonochromatic (such as green color, red color, blue color, or the like)light emitting panel.

Next, procedures for manufacturing the light emitting device willhereinafter be described. A substrate with an anode (the firstelectrode) and an insulator (partition wall) covering edge portions ofthe anode previously formed thereon is transported into themanufacturing device as depicted in FIG. 5, thereby the light emittingdevice is manufactured. In case of manufacturing an active matrix typelight emitting device, a plurality of thin film transistors (currentcontrolling TFTs) connected to the anode, a plurality of other thin filmtransistors (switching TFTs), and driver circuits including thin filmtransistors are formed over the substrate in advance. Meanwhile, it isalso possible to manufacture a simple matrix type light emitting deviceby means of the manufacturing device as depicted in FIG. 5.

At first, the substrate (600 mm×720 mm) is set in a substrateinstallation chamber 520. A large area substrate having a size of, forexample, 320 mm×400 mm, 370 mm×470 mm, 550 mm×650 mm, 600 mm×720 mm, 680mm×880 mm, 1000 mm×1200 mm, 1100 mm×1250 mm or 1150 mm×1300 mm may alsobe employed.

The substrate (on which the anode and the insulator covering the edgeportion of the anode are formed) that is set in the substrateinstallation chamber 520 is transported into a transporting chamber 518.A transporting mechanism (such as a transporting robot) for transportingor inverting the substrate is provided in the transporting chamber 518.

In the transporting chambers 508, 514, and 502, the transportingmechanisms and vacuum exhaust means are provided, respectively. Thetransporting robot provided in the transporting chamber 518 can invertthe substrate and transport the inverted substrate into a deliverychamber 505. Since the delivery chamber 505 is connected to a vacuumexhaust processing chamber, the inside of the delivery chamber 505 canbe vacuum-exhausted to be in a vacuum state, or after vacuum exhaust, aninert gas is introduced to produce an atmospheric pressure in thedelivery chamber 505.

Moreover, the vacuum exhaust processing chamber is equipped with amagnetic levitated type turbo molecular pump, a cryopump, or a dry pump.By utilizing these pumps, it is possible to make the ultimate pressureof the transporting chamber be 10⁻⁵ to 10⁻⁶ Pa, and further, reversediffusion of impurities from the pump side and exhaust system can becontrolled. In order to prevent impurities from being introduced intothe interior of the apparatus, an inert gas such as nitrogen gas andrare gas are used as a gas to be introduced. For these gases introducedinto the apparatus, gases highly purified by a gas purifier prior to theintroduction into the interior of the apparatus are used. Therefore, itis required that a gas purifier is implemented so that the gas isintroduced into the evaporation apparatus following the highpurification of the gas. Since by utilizing this, oxygen, moisture andother impurities contained in the gas can be previously removed, whichprevents the impurities from being introduced into the interior of theapparatus.

Prior to installation of the substrates into the substrate installationchamber 520, in order to reduce point defects, it is preferable that asurface of the first electrode (anode) is cleaned by using a poroussponge (for example, being made of polyvinyl alcohol (PVA), or nylon)impregnated with surfactant (being alkalescent), thereby washing awaydust from a surface thereof. As for a cleaning mechanism, a cleaningdevice having a roll brush (for example, made of PVA) which contacts aface of a substrate such that the roll brush rotates around an axis lineparallel to the surface of the substrate may be used, or anothercleaning device having a disk brush (for example, made of PVA) whichcontacts a surface of a substrate such that the disk brush rotatesaround an axis line vertical to the surface of the substrate may beused.

The substrate is transported from the transporting chamber 518 into thedelivery chamber 505, and further the substrate is transported from thedelivery chamber 505 to the transporting chamber 502 without beingexposed to the atmospheric air.

Further, it is preferable to perform vacuum heating just beforeevaporation of the film containing the organic compound in order toprevent a shrinkage, and the substrate is transferred from thetransporting chamber 502 into the multistage vacuum heating chamber 521and annealing for degassing is performed in vacuum (less than 5×10⁻³Torr (0.665 Pa), preferably 10⁻⁴ to 10⁻⁶ Pa), in order to removemoisture and other gas contained in the above substrate completely. Inthe multistage vacuum heating chamber 521, a flat heater (typically, asheath heater) is used to heat a plurality of substrates uniformly. Aplurality of the flat heaters can be disposed to heat the substrate fromboth sides as sandwiching the flat heaters. Of course, the flat heatercan heat the substrate from one side.

Particularly, when an organic resin film is used as a material for aninterlayer insulating film or a barrier wall, some organic resinmaterials tend to absorb moisture, which could lead to furtherdeaeration. Thus, it is effective to perform vacuum heating in which thesubstrate is annealed at temperatures of 100 to 250° C., preferably 150to 200° C. for 30 minutes or more, and then naturally cooled for 30minutes, for example, to remove absorbed moisture before the layercontaining organic compounds is deposited.

In addition to vacuum heating, ultraviolet ray (UV) may be irradiated tothe substrate during heating at 200 to 500° C. under an inert gasatmosphere. Further, without conducting the vacuum heating, it is alsopossible to carry out a UV irradiating treatment while the substrate isheated at 200 to 500° C. under the inert gas atmosphere.

In the film formation chamber 512, a hole injection layer may be formedof a polymeric material by ink jetting, spin coating, spraying or thelike under the atmospheric pressure or reduced pressure, if necessary.Further, after the application by ink jetting, the film thickness may beuniformized by use of a spin coater. As well as ink jetting, after theapplication is carried out by spraying, the film thickness may also beuniformized by use of the spin coater. Furthermore, the film formationmay be carried out by vertically setting the substrates in a vacuum byink jetting.

In the film formation chamber 512, for instance, an aqueous solution ofpoly(ethylene dioxythiophene)/poly(styrene sulfonic acid) (PEDOT/PSS),an aqueous solution of polyaniline/camphor sulfonic acid (PANI/CSA),PTPDES, Et-PTPDEK, PPBA, or the like, which acts as a hole injectionlayer (anode buffer layer) may be applied over the entire surface of thefirst electrode (anode), and fired. It is preferable to perform firingin multistage heating chambers 523 a and 523 b.

Levelness can be improved for cases in which a hole injection layer(HIL) made of a high molecular weight material formed by an applicationmethod using a spin coater or the like. The coverage and uniformity infilm thickness are made satisfactory for films formed thereupon. Inparticular, uniform light emission can be obtained since the filmthickness of the light emitting layers becomes uniform. In this case, itis preferred to perform vacuum heating (at 100 to 200° C.) after formingthe hole injection layer by application, and immediately before filmformation by vapor deposition.

Note that processes of the invention is performed, for example, by thefollowing processes including: the surface of the first electrode(anode) is cleaned by using a sponge; the substrate is carried in thesubstrate installing chamber 520 and transferred to the film formationchamber 512 a; an aqueous solution of poly(ethylenedioxythiophene)/poly(styrene sulfonic acid) (PEDOT/PSS) is applied onthe entire surface of the first electrode by spin coating to a filmthickness of 60 nm; the substrate is transferred to the multistageheating chambers 523 a and 523 b and is provisionally fired at 80° C.for 10 minutes, and then fired at 200° C. for one hour; the substrate istransferred to the multistage vacuum heating chamber 521, vacuum heating(heating for 30 minutes at 170° C., then cooling for 30 minutes) isperformed immediately before evaporation; and the substrate istransported to the film formation chambers 506W1, 506W2, 506W3 and theEL layer is formed by evaporation without exposure to the air. Inparticular, in case that the ITO film is used as the anode andunevenness or minute particles exists on the surface of the ITO film,the adverse influences of unevenness or minute particles can be reducedby making the PEDOT/PSS film with a thickness of not less than 30 nm.Further, ultraviolet irradiation is preferably performed in an UVtreatment chamber 531 in order to improve the wettability of thePEDOT/PSS film.

Further, the PEDOT/PSS film is formed over the entire surface whenPEDOT/PSS is formed by spin coating, and therefore it is preferable toselectively remove the PEDOT/PSS film from edge surfaces and peripheralportions of the substrate, and regions that connect to terminalportions, connecting regions between the cathodes and lower wirings, andthe like. It is preferable to remove the PEDOT/PSS film by employing O₂ashing or the like using a mask in the pretreatment chamber 503. Thepretreatment chamber 503 has a plasma generating means, and dry etchingis performed by exciting one gas or a plurality of gases selected fromAr, H, F, and O, thus generating a plasma. By using the mask,unnecessary portions can be selectively removed.

Note that the evaporation mask is stocked in mask stacking chambers 524a and 524 b and is arbitrarily transferred to the film formation chamberwhen vapor deposition is carried out. Since the mask area is enlargedwhen a large size substrate is used, a frame for fixing the substratebecomes larger. Therefore, it is difficult to stock a lot of masks inone mask stocking chamber. In Embodiment Mode 2, two mask stockingchambers are provided for the sake of overcoming the aforementionedproblem. Cleaning of the evaporation mask may be performed in the maskstocking chambers 524 a and 524 b. Further, when performing vapordeposition, the mask stocking chambers are available, which permits tostock substrates with films formed thereon or processed substrates.

The substrates are transferred from the transporting chamber 502 intothe transporting chamber 508 via the delivery chamber 507 withoutexposing the substrate in the atmospheric air.

The substrates are further sequentially transferred to the filmformation chambers 506W1, 506W2 and 506W3, which are connected to thetransporting chamber 508 such that organic compound layers formed of alow-molecular-weight compound material, which will respectively serve asthe hole transporting layer, the light emitting layer, and the electrontransporting layer, are arbitrarily formed. The organic compound layersare formed by arbitrarily selecting the EL materials, which makes itpossible to form the light emitting element emitting monochromatic light(specifically, white color light) by the whole light emitting element.Note that the substrates are transferred to the respective transportingchambers via the delivery chambers 540, 541, and 511 without beingexposed to the atmospheric air.

Next, the substrate is transported into the film formation chamber 510by a transporting mechanism provided in the transporting chamber 514such that a cathode is formed over the substrate in the film formationchamber 510. The cathode is preferably formed of a transparent materialor a translucent material. More specifically, following materials arepreferably used as the cathode: a thin film (with a thickness of 1 to 10nm) of metal film (a film of an alloy of, for example, MgAg, MgIn,inorganic material of CaF₂, LiF, or CaN, a film formed by using anelement belonging to group I or II in the periodic table and aluminum bymeans of coevaporation, or a laminate thereof) formed by vapordeposition utilizing resistive heating; or a lamination layer of theaforementioned thin metal film (with a thickness of 1 to 10 nm) and thetransparent conductive film. The substrate is transported from thetransporting chamber 508 into the transporting chamber 514 via thedelivery chamber 511, and then the substrate is subsequently transportedinto the film formation chamber 509 so as to form the transparentconductive film by sputtering.

The light emitting element having a lamination structure which includesthe layer containing the organic compound is formed according to theaforementioned processes.

It is also possible to transfer the substrate into the film formationchamber 513 connected to the delivery chamber 514 so as to form aprotective film containing a silicon nitride film or a siliconoxynitride film. Here, a target containing silicon, a target containingsilicon oxide, or a target containing silicon nitride is provided in thefilm formation chamber 513.

The protective film may be formed by moving a rod-shaped target relativeto the fixed substrate. Further, the protective film may be formed bymoving the substrate relative to a fixed rod-shaped target.

For instance, by using a disk target containing silicon, an atmospherein the film formation chamber is set to be a nitrogen atmosphere or anatmosphere containing nitrogen and argon, so that a silicon nitride filmcan be formed over the cathode. A thin film (DLC film, CN film, oramorphous carbon film) containing carbon as its main component may beformed as a protective film, and a film formation chamber using CVD maybe additionally provided. A diamond-like carbon film (also referred toas a DLC film) can be formed by plasma CVD (typically, RF plasma CVD,microwave CVD, electron cyclotron resonance (ECR) CVD, hot-filament CVD,or the like), a combustion flame method, sputtering, ion-beamevaporation, laser evaporation, or the like. A reaction gas used in thefilm formation is a hydrogen gas and a hydrocarbon group gas (forexample, CH₄, C₂H₂, C₆H₆, or the like). The reaction gas is ionized byglow discharge, and resultant ions are accelerated and impacted to thecathode which is negatively self-biased to form a film. A CN film may beformed by using C₂H₄ gas and N₂ gas as reaction gases. The DLC film andthe CN film are insulating films which are transparent or translucentwith respect to visible light. The transparency with respect to thevisible light means that a transmittance of the visible light rangesfrom 80 to 100%, and the translucence means that a transmittance of thevisible light ranges 50 to 80%.

As a substitute for the above-mentioned protective film, it is possibleto form a protective film by laminating the first inorganic insulatingfilm, a stress relaxation layer, and the second inorganic insulatingfilm. For instance, it is permissible that, after the cathode is formed,the substrate is transported into the film formation chamber 513 wherethe first inorganic insulating film is formed with a thickness of 5 to50 nm, and, then the resultant substrate is transported into the filmformation chamber 506W1, 506W2, or 506W3 where the stress relaxationlayer (such as an inorganic layer, and a layer containing an organiccompound) having a hygroscopic property and transparency is formed to athickness of 10 to 100 nm thereon and, thereafter, the resultantsubstrate is transported back to the film formation chamber 513 wherethe second inorganic insulating film is formed thereon with a thicknessof 5 to 50 nm.

Next, the substrate on which the light emitting element is formed istransported into the sealing chamber 519.

A sealing substrate is set in a loading chamber 517 from the outside andready to be processed. The sealing substrate is transported from theloading chamber 517 into the transporting chamber 527. The sealingsubstrate is further transported into an optical film bonding chamber529 for bonding a desiccant or an optical filter (such as a colorfilter, and a polarizing film), if required. In addition, the sealingsubstrate attached with the optical film (such as the color filter and apolarizing plate) thereto may be previously set in the loading chamber517.

In order to remove impurities such as moisture contained in the sealingsubstrate, annealing is preferably performed in the multistage heatingchamber 516 in advance. In case of forming a sealing material forbonding the substrate with the light emitting element formed thereon tothe sealing substrate, the sealing material is formed in a dispenserchamber 515, and the sealing substrate with the sealing material formedthereon is transported into the transporting chamber 514 via thedelivery chamber 542, and then the resultant sealing substrate istransported into the sealing substrate stocking chamber 530. Note that,although an example of forming the sealing material on the sealingsubstrate is shown here, the present invention is not particularlylimited thereto, and the sealing substrate may be formed over thesubstrate on which the light emitting element is formed. Further, theevaporation mask, which is used in vapor deposition, may be stocked inthe sealing substrate stocking chamber 530.

When the dual-sided light emission structure is formed according toEmbodiment Mode 2, the sealing substrate may be transported into theoptical film bonding chamber 529, and the optical film may be attachedto inside of the sealing substrate. Or, after bonding the substrate withthe light emitting element formed thereon and the sealing substrate, thesealing substrate may be transported into the optical film bondingchamber 529, and then the optical film (the color filter or thepolarizing plate) is attached to the outside of the sealing substrate.

Next, the substrate and the sealing substrate is bonded in the sealingchamber 519, a UV light is irradiated to the pair of substrates bondedto each other by use of an ultraviolet irradiation mechanism that isprovided in the sealing chamber 519 so as to cure the sealing material.It is preferred to irradiate the UV light from the sealing substrateside where is not provided with a TFT that shields light. The sealingmaterial formed by mixing UV curing resin and a thermosetting resin isused as the sealing material here. However the present invention is notlimited thereto as long as it is an adhesive, and only the UV curingresin may also be used.

The sealed space may not be filled with the inert gas, but may be filledwith resin. When the UV light is irradiated from the sealing substrateside in case of a bottom emission type, since the cathode does not allowlight to pass therethrough, the resin material filled to the sealedspace is not particularly limited, and the UV curing resin or a opaqueresin may be used. On the other hand, when the ultraviolet light isirradiated from the sealing substrate side in case of a dual sided lightemission type, the UV light passes through the cathode, causing damageagainst the EL layer. Therefore, it is preferable that the UV curingresin is not used in case of the dual-sided emission type. As result, incase of the dual sided light emission type, the transparentthermosetting resin is preferably used for the resin filled to thesealed space.

Subsequently, the bonded pair of substrates is transported from thesealing chamber 519 into the transporting chamber 514, and then the pairof substrates is taken out from the transporting chamber 527 into anextraction chamber 525 via the delivery chamber 542.

After taking out the pair of substrates from the extraction chamber 525,the sealing material is cured by a heating treatment. When thethermosetting resin is filled in the sealed space in case of the topemission type, the thermosetting resin can be cured along with theheating treatment of the sealing material at the same time.

As set forth above, by using the manufacturing apparatus as depicted inFIG. 5, the light emitting element can be completely formed until it isencapsulated in the sealed space without being exposed into theatmospheric air, permitting the fabrication of the light emitting devicewith high reliability.

Note that a controlling apparatus, which realizes total automation bycontrolling a pathway along with which the substrate is moved into eachtreatment chamber, is provided in the manufacturing apparatus, althoughit is not illustrated in the drawings.

EMBODIMENTS

The present invention that includes the above-described structure willbe described in more detail with the following embodiments.

Embodiment 1

In Embodiment 1, shown is an example of manufacturing a light emittingdevice (having a dual-sided light emitting constitution) provided over asubstrate having an insulating surface with a light emitting element inwhich an organic compound layer is allowed to be a light emitting layerwith reference to FIGS. 3A and 3B.

FIG. 3A is a top view showing the light emitting device and FIG. 3B is across sectional view of FIG. 3A taken along a line A-A′. Referencenumeral 1101 indicated by a dotted line designates a source signal linedriving circuit, reference numeral 1102 designates a pixel portion, andreference numeral 1103 designates a gate signal line driving circuit.Further, reference numeral 1104 designates a transparent sealingsubstrate, reference numeral 1105 designates a first sealing material,and an interior surrounded by the first sealing material 1105 is filledwith a transparent second sealing material 1107. The first sealingmaterial 1105 contains a gap material for securing a space betweensubstrates.

Reference numeral 1108 denotes a wiring for transmitting signals to beinputted to the source signal line driving circuit 1101 and the gatesignal line driving circuit 1103. The wiring 1108 receives a videosignal or a clock signal from a flexible printed circuit (FPC) 1109which is an external input terminal. Although only the FPC 1109 isillustrated in the drawing, a printed wiring board (PWB) may beattached.

Subsequently, a sectional constitution will be described with referenceto FIG. 3B. Although a driver circuit and a pixel portion are formedover a transparent substrate 1110, the source signal line drivingcircuit 1101 and the pixel portion 1102 are shown as the driver circuitin FIG. 3B.

In the source signal line driving circuit 1101, a CMOS circuit in whichan n-channel type TFT 1123 and a p-channel type TFT 1124 are combined isformed. The TFT which constitutes the driver circuit may be formed by atleast one circuit selected from the group consisting of: a CMOS circuit,a PMOS circuit and an NMOS circuit which are publicly known in the art.In Embodiment 1, a driver-integrated type in which the driver circuit isformed over the substrate is shown, however, the driver-integrated typemay not necessarily be adopted. The driver circuit can also be formedoutside the substrate instead of being formed over the substrate. Aconstitution of the TFT using a polysilicon film or an amorphous siliconfilm as an active layer is not particularly limited thereto, either atop gate type TFT or a bottom gate type TFT is permissible.

The pixel portion 1102 is formed by a plurality of pixels each of whichincludes a switching TFT 1111, a current-controlling TFT 1112 and thefirst electrode (anode) 1113 which is electrically connected to thedrain of the current-controlling TFT 1112. The current-controlling TFT1112 may either be an n-channel type TFT or a p-channel type TFT, butwhen it is to be connected to the anode, it is preferably the p-channeltype TFT. It is also preferable that a storage capacitor (not shown) isappropriately provided. An example in which only a cross-sectionalconstitution of one pixel is shown where two TFTs are used in the pixelis illustrated, but three or more TFTs may appropriately be used perpixel.

Since the first electrode 1113 is directly connected to the drain of theTFT 1112, it is preferable that a lower layer of the first electrode1113 is allowed to be a material layer which can have an ohmic contactwith the drain containing silicon, while an uppermost layer thereofwhich contacts a layer containing an organic compound is allowed to be amaterial layer which has a large work function. For example, atransparent conductive film (ITO (indium tin oxide alloy), indium oxidezinc oxide alloy (In₂O₃—ZnO), zinc oxide (ZnO) or the like) may be used

An insulator 1114 (referred to as a bank, a partition wall, a barrier,an embankment and the like) is formed over each end of the firstelectrode (anode) 1113. The insulator 1114 may be formed by either anorganic resin film or an insulating film containing silicon. In thepresent embodiment, as for the insulator 1114, an insulator is formed ina shape as shown in FIG. 3B by using a positive type photosensitiveacrylic resin film.

For the purpose of enhancing a coverage effect, a curved surface havinga curvature is to be formed in an upper end portion or a lower endportion of the insulator 1114. For example, when the positive typephotosensitive acrylic resin is used as a material for the insulator1114, it is preferable that a curved surface having a curvature radius(0.2 μm to 3 μm) is provided only to the upper end portion of theinsulator 1114. As for the insulator 1114, either one of a negative typewhich becomes insoluble to an etchant by light, and a positive typewhich becomes soluble to the etchant by the light can be used.

Further, the insulator 1114 may be covered by a protective film formedof a thin film containing at least one film selected from an aluminumnitride film, an aluminum oxynitride film, a thin film containing carbonas its main component or a silicon nitride film.

A layer 1115 containing an organic compound is selectively formed overthe first electrode (anode) 1113 by vapor deposition. In Embodiment 1,the layer 1115 containing the organic compound is formed by themanufacturing apparatus as described in Embodiment Mode 2 so as to havea uniform film thickness. Further, the second electrode (cathode) 1116is formed over the layer 1115 containing the organic compound. As forthe cathode, a material having a small work function (for example Al,Ag, Li, Ca, alloys of thereof, that is, MgAg, MgIn, AlLi, inorganicmaterials such as CaF₂, or CaN) may be used. In Embodiment 1, in orderto allow luminescence to pass through the cathode, as for the secondelectrode (cathode) 1116, a laminate of a thin metal film which is thinin thickness (MgAg: film thickness of 10 nm), and a transparentconductive film with a film thickness of 110 nm (indium tin oxide alloy(ITO)), an indium oxide-zinc oxide alloy (In₂O₃—ZnO), or zinc oxide(ZnO)) is used. Then, a light emitting element 1118 including the firstelectrode (anode) 1113, the layer 1115 containing the organic compound,and the second electrode (cathode) 1116 is fabricated. In the presentembodiment, the layer 1115 containing the organic compound is formed bysequentially laminating CuPc (film thickness of 20 nm), α-NPD (filmthickness of 30 nm), CBP (film thickness of 30 nm) including an organicmetal complex that contains platinum as its central metal (Pt(ppy)acac),BCP (film thickness of 20 nm), and BCP:Li (film thickness of 40 nm),thereby realizing white color light emission. In the present embodiment,the light emitting element 1118 is allowed to be an example of emittingwhite light, and therein, a color filter (for the purpose of simplicity,an overcoat layer is not illustrated in the drawings) including acolored layer 1131 and a light shielding layer (BM) is provided.

A transparent protective layer 1117 is formed in order to seal the lightemitting element 1118. The transparent protective layer 1117 is formedby laminating a first inorganic insulating film, a stress relaxationfilm and a second inorganic insulating film. As for each of the firstand second inorganic insulating films, at least one film selected fromthe group consisting of: a silicon nitride film, a silicon oxide film, asilicon oxynitride film (SiNO film (composition ratio: N>O), or SiONfilm (composition ratio: N<O)), and a thin film containing carbon as itsmain component (for example, DLC film, or CN film) which are obtained bysputtering or CVD can be used. These inorganic insulating films eachhave a high blocking effect against moisture, however, as film thicknessthereof is increased, a film stress is increased, then, they tend to bepartially peeled or totally removed. However, stress can be relaxed and,also, moisture can be absorbed by interposing the stress relaxation filmbetween the first inorganic insulating film and the second inorganicinsulating film. Even when a minute hole (pinhole or the like) is formedin the first inorganic insulating film by some reasons, the minute holecan be filled by the stress relaxation film and, further, by providingthe second inorganic insulating film thereover, an extremely highblocking effect against moisture or oxygen can be attained. As formaterials for the stress relaxation film, a material which has smallerstress than the inorganic insulating films and has a hygroscopicproperty is preferable. In addition to the above-described properties, amaterial having a translucency is desirable. Further, as for the stressrelaxation film, a material film containing an organic compound such asa-NPD (4,4′-bis [N-(naphthyl)-N-phenyl-amino]biphenyl), BCP(bathocuproin), MTDATA(4,4′,4″-tris(N-3-methylphenyl-N-phenyl-amino)triphenylamine, and Alq₃(a tris-8-quinolinolate aluminum complex) may be used. Each materialfilm has a hygroscopic property. When they are thin in thickness, theybecome nearly transparent. Since MgO, SrO₂, and SrO each have ahygroscopic property and translucency, and also, a thin film thereof canbe obtained by vapor deposition, any one of these oxides can be used asthe stress relaxation film. In the present embodiment, a silicon targetis used, a film formed in an atmosphere containing a nitrogen gas and anargon gas, that is, a silicon nitride film having a high blocking effectagainst impurities such as moisture and an alkali metal is used as thefirst inorganic insulating film or the second inorganic insulating film,and a thin film of Alq₃ formed by vapor deposition is used as the stressrelaxation film. Further, in order to allow luminescence to penetratethe transparent protective laminate, it is preferable that an entirefilm thickness of the transparent protective laminate is formed as thinas possible.

Further, in order to seal the light emitting element 1118, the sealedsubstrate 1104 is bonded thereto by using the first sealing material1105 and the second sealing material 1107 in an inert gas atmosphere. Asfor the first sealing material 1105, it is preferable that an epoxyresin is used. As for the second sealing material 1107, the material isnot particularly limited as long as it is a material havingtranslucency, and a UV curing epoxy resin or a thermosetting epoxy resinare typically used. A highly heat resistant UV curing epoxy resin(product name 2500 Clear, manufactured by Electrolite Cooperation)having a refractive index of 1.50, a viscosity of 500 cps, a Shore Dhardness of 90, a tensile strength of 3,000 psi, a Tg point of 150° C.,a volume resistivity of 1×10¹⁵ Ω·cm, and a withstand voltage of 450V/mil is used here. As compared with the case in which the gap betweenthe pair of substrates is a space (inert gas), the overall transmittancecan be enhanced by filling the second sealing material 1107 between thepair of substrates. The first sealing material 1105 and the secondsealing material 1107 are preferably formed of materials which do notallow to penetrate moisture and oxygen as little as possible.

Further, in the present embodiment, a plastic substrate comprising atleast one member consisting of: fiberglass-reinforced plastics (FRP),polyvinylfluoride (PVF), Mylar, polyester, an acrylic resin, and thelike, other than a glass substrate or a quartz substrate can be used asa material which constitutes the sealing substrate 1104. After thesealing substrate 1104 is bonded by using the first sealing material1105 and the second sealing material 1107, it is possible to performsealing by using the third sealing material such that a side surface(exposed face) is covered.

By sealing the light emitting element in the first sealing material 1105and the second sealing material 1107 as described above, the lightemitting element can completely be shielded from outside. Inconsequence, substance, such as moisture and oxygen, which willdeteriorate the organic compound layer, can be prevented frompenetrating from the outside. As result, a light emitting device havinghigh reliability can be obtained.

Further, this embodiment can be freely combined with Embodiment Mode 1.

Embodiment 2

In Embodiment 2, an example of an electronic equipment provided with twoor more display devices will be described with reference to FIGS. 4A to4F. An electronic equipment equipped with an EL module can be completedby implementing the present invention. The following are examples ofelectronic equipment: video cameras, digital cameras, goggle typedisplays (head mounted displays), navigation systems, audio reproducingapparatuses (car audios, audio components, etc.), laptop computers, gamemachines, portable information terminals (mobile computers, cellularphones, portable game machines, electronic books, etc.), imagereproducing apparatuses equipped with a recording medium (specifically,devices equipped with displays each of which is capable of playing arecording medium such as a digital versatile disk (DVD), and displayingthe image thereof), and the like.

FIG. 4A is a perspective view showing a laptop computer, and FIG. 4B isalso a perspective view showing a folded laptop computer. Each lap topcomputer comprises a main body 2201, a casing 2202, display portions2203 a and 2203 b, a keyboard 2204, an external connection port 2205, apointing mouse 2206, etc.

The laptop computers as illustrated in FIGS. 4A and 4B are equipped withthe display portion 2203 a that mainly displays full color image and thedisplay portion 2203 b that mainly displays characters and symbols inmonochrome.

FIG. 4C is a perspective view showing a mobile computer, which comprisesa main body 2301, display portions 2302 a and 2302 b, switches 2303,operation keys 2304, an infrared port 2305, etc. The mobile computerincludes the display portion 2302 a that mainly displays full colorimage and the display portion 2302 b that mainly displays characters andsymbols in monochrome.

FIG. 4E shows a video camera, which comprises a main body 2601, adisplay portion 2602, a casing 2603, an external connection port 2604, aremote-controlled receiving portion 2605, an image receiving portion2606, a battery 2607, an audio input portion 2608, operation keys 2609,etc. The display portion 2602 is a dual-sided emission panel in whichone of the screen can mainly display high-definition full color imageand another screen can mainly display characters and symbols inmonochrome. The display portions 2602 can rotate at an attachmentportion. The present invention can be applied to the display portion2602.

FIG. 4F is a perspective view showing a cellular phone, and FIG. 4G isalso a perspective view showing a folded cellular phone. Each cellularphone comprises a main body 2701, a casing 2702, display portions 2703 aand 2703 b, an audio input portion 2704, an audio output portion 2705,operation keys 2706, an external connection port 2707, an antenna 2708,etc.

The cellular phones as depicted in FIGS. 4F and 4G include the displayportions 2703 a that mainly display high-definition full color image andthe display portions 2703 b that mainly display characters and symbolsby an area color mode. In this case, a color filter is used for thedisplay portion 2703 a, whereas an optical film that becomes an areacolor is used for the display portion 2703 b.

Further, this embodiment can be freely combined with Embodiment Modesand Embodiment 1.

Embodiment 3

An example of a top view of an evaporation device will be illustrated inFIG. 6.

In FIG. 6, a film formation chamber 101 includes a substrate holder (notillustrated), a first evaporation source holder 104 a and a secondevaporation source holder 104 b installed with evaporation shutters (notillustrated), a means for moving the evaporation source holders (notillustrated) and a means for producing a low pressure atmosphere (i.e.,a vacuum exhaust means). Further, the film formation chamber 101 isvacuum-exhausted to a vacuum degree of not more than 5×10⁻³ Torr (0.665Pa), preferably, 10⁻⁴ through 10⁻⁶ Pa by use of the means for producingthe low pressure atmosphere.

Further, the film formation chamber 101 is connected to a gasintroduction system for introducing a material gas to several sccm invapor deposition (not illustrated) and an inert gas (such as Ar, and N₂)introduction system for restoring a normal pressure in the filmformation chamber (not illustrated). In addition, a cleaning gas (a gaswhich is one element or a plural elements selected from a groupconsisting of H₂, F₂, NF₃, and O₂) introduction system may be formed. Itis preferable that each introduction system is formed so as not to allowthe material gas to flow from a gas introduction port into a gasevacuation port by the most direct way.

It is possible that the material gas is intentionally introduced duringvapor deposition, and the organic compound film is saturated with thecomponent of the material gas so as to form a high density film, therebyblocking impurities such as oxygen and moisture, which causedeterioration of the film, from intruding and diffusing. As the materialgas, more specifically, one kind or a plural kinds selected from asilane group gas (such as monosilane, disilane and trisilane), SiF₄,GeH₄, GeF₄, SnH₄ and hydrocarbon group gas (such as CH₄, C₂H₂, C₂H₄ andC₆H₆) may be used. Note that a mixed gas in which aforementioned gasesare diluted by hydrogen, argon and the like may also used as thematerial gas. Before the gas is introduced inside the device, the gas ishighly purified by a gas purifier. Accordingly, it is necessary toprovide the gas purifier so that after the gas is highly purified, thegas is introduced into the evaporation device. A residual gas (such asoxygen, moisture and other impurities) contained in the gas can bepreviously removed. Therefore, it is possible to prevent theseimpurities from being introduced inside the device.

When the light emitting element has defect portions such as pin holesand short circuits after the light emitting element containing Si iscompletely formed, a monosilane gas is introduced in vapor depositionsuch that Si reacts and forms an insulator such as SiOx and SiCx due toheat generation in the defect portions, which reduces leakage in the pinholes and the short circuits. As result, point defects (dark spots etc.)are not expanded, and, hence, a self-healing effect can be obtained.

When above-mentioned material gas is introduced, in addition to thecryopump, it is preferable to use a turbo molecular pump or a dry pump.

In the film formation chamber 101, the evaporation source holder 104 canmove along a migration course as depicted by a chained line in FIG. 6 atmultiple times. FIG. 6 shows only one example of the migration course ofthe evaporation source holder, and it is not limited to the example. Inorder to improve the uniformity of the film thickness, the vapordeposition is preferably carried out by shifting the migration course soas to move the evaporation source holder 104 as illustrated in FIG. 6.Further, the evaporation source holder may also be moved back and forthalong an identical migration course. Furthermore, it is possible touniformize the film thickness by arbitrarily changing the migration rateof the evaporation source holder in each migration course zone such thattime for the film formation is reduced. For instance, the evaporationsource holder may be shifted in the X direction or the Y direction at arate of 30 cm/min to 300 cm/min.

When the white color light emitting element is manufactured, it ispossible to perform vapor deposition locally as illustrated in FIG. 9.The vapor deposition is locally carried out so as to include at leastthe regions to be display regions within the regions to be panels. Byperforming vapor deposition locally, it is possible to prevent regionsthat are unnecessary to be evaporated from being evaporated. In order toevaporate locally on the regions to be display regions, shutters (notillustrated) are used. Vapor deposition is performed by arbitrarilyopening or closing the shutters without using masks. FIG. 9 is anexample of a case of mass production, and reference numeral 900 denotesa large size substrate, reference numeral 901 denotes a film formationchamber, reference numeral 904 denotes a movable evaporation sourceholder, and reference numeral 906 denotes a crucible.

Containers (crucibles 106) encapsulated with an evaporation material areset in the evaporation source holders 104 a and 104 b. This embodimentshows an example in which each evaporation source holder 104 a and 104 bincludes two crucibles, respectively. In the installation chamber 103, afilm thickness meter (not illustrated) is provided. In this embodiment,during the migration of the evaporation source, the film thickness isnot monitored by the film thickness meter so as to reduce exchangefrequency of the film thickness meter.

When a plurality of containers (such as crucibles that accommodate anorganic compound, and evaporation boats) are equipped in one evaporationsource holder, it is preferable to set the mounting angle of thecrucibles obliquely such that the evaporation directions (i.e.,evaporation center) intersect at a position of a substance that isevaporated in order to mix each organic compound.

The evaporation source holder always stands in a crucible installationchamber, and heats and maintains temperature until the evaporation ratebecomes stable. The film thickness meter (not illustrated) is installedin the crucible installation chamber. When the evaporation rate becomesstable, the substrate is transported into the film formation chamber 102, and after masking (not illustrated) and aligning is carried out, theshutter is opened to transfer the evaporation source holder. Note thatthe alignment of the evaporation mask and the substrate is preferablyconfirmed by using a CCD camera (not illustrated). Alignment markers maybe provided in the substrate and the evaporation mask so as to performthe alignment control thereof. When vapor deposition is finished, theevaporation source holder is transferred into the crucible installationchamber, and then the shutter is closed. When the shutter is closedcompletely, the resultant substrate is transported into the transportingchamber 102.

In FIG. 6, a plurality of evaporation source holders can stand in theinstallation chamber 103. Therefore, when a material in one evaporationsource holder is run out, the evaporation source holder is replaced withanother one evaporation source holder and sequentially changed theevaporation source holders, permitting film formation in succession. Inaddition, it is possible to replenish an EL material in the emptyevaporation source holder while other evaporation source holder istransported in the film formation chamber. The film formation can beefficiently carried out by using the plurality of evaporation sourceholders 104.

In FIG. 6, the evaporation source holders 104 a and 104 b accommodateonly tow crucibles. However, it is also possible to use a evaporationsource holder which can accommodate four crucibles, although only onecrucible or two crucibles are set in the crucibles.

According to the present invention, time for forming films can bereduced. Conventionally, in case of replenishing the EL material in theempty evaporation source holder, after the film formation chamber hasbeen exposed to the atmospheric air and the EL material has beenreplenished in the crucible, the interior of the film formation chamberhas been necessary to be vacuum-exhausted. Therefore, the time requiredfor replenishing the EL material has been prolonged, causingdeterioration in through put.

If the EL material is hardly adhered to an inner wall of the filmformation chamber, the frequency of maintenance such as cleaning in theinner wall of the film formation chamber can be lessened.

Setting of the crucible 106 in the evaporation source holders 104 a and104 b is also carried out in the installation chamber 103 b. FIGS. 7A to7C show the condition of transporting the crucible 106. In FIGS. 7A to7C, same reference numerals are used for corresponding portions in FIGS.6. The crucible 106 which is sealed with vacuum in a container consistedof an upper part 721 a and a lower part 721 b is transported through adoor 112 of an installation chamber 103. At first, the transportedcontainer is placed on the turntable for installing a container 109 in astate where the fastener 702 is unclasped in the installation chamber.Since the inside of the installation chamber is under vacuum, thecontainer is as it is when the fastener 702 is unclasped (see FIG. 7A).Subsequently, an interior of the installation chamber 103 a isvacuum-exhausted so as to uncouple a cover (i.e., the upper part 721 a)from the lower part 721 b.

The condition of transporting the container will be described in moredetail with reference to FIG. 7A. A second container has two portions ofan upper psrt (721 a) used for transporting and a lower part (721 b) andcomprises fixing means 706 for fixing a first container (crucible)provided in the upper part of the second container; a spring 705 forapplying pressure to the fixing means; a gas introduction port 708 atthe lower part of the second container, which serves as a gas pathwayfor maintaining a reduced pressure in the second container; an O-ringthat fixes the upper portion container 721 a and the lower portioncontainer 721 b; and a fastener 702. A first container 106, in which apurified evaporation material is filled, is set in the second container.In addition, the second container is preferable to be made of a materialcontaining stainless, and the first container 106 is preferable to bemade of a material containing titanium.

A purified evaporation material is filled in the first container 106 atthe material manufacturer. The second upper part 721 a and the secondlower part 721 b are bonded to each other using the O-ring and fixedusing the fastener 702. The first container 106 is hermetically sealedin the second container, then, the second container is reduced pressureand substituted for a nitrogen atmosphere through the gas introductionport 708, and then, the first container 106 is fixed by adjusting thespring 705 with the fixing means 706. In addition, a desiccant can beput into the second container. Consequently, maintaining a vacuum, lowpressure, or nitride atmosphere in the second container can prevent eventrace amount of oxygen or moisture from adhering to the evaporationmaterial.

The cover of the container is lifted by means of a robot fortransporting a cover 108 so as to be put on a cover installation table107. Note that the transporting means of the present invention is notlimited to the structure as described in FIGS. 7B and 7C, in which thefirst container 106 is sandwiched (picked up) from above the firstcontainer. Structures in which sides of the first container aresandwiched by the robot for transporting a cover 108 so as to transportthe first container 106 may also be employed.

After rotating the turntable for installing the container 109, only thecrucible is lifted by the crucible-transporting robot 110 while leavingthe lower part of the container on the turntable 109. Finally, thecrucible is set in the evaporation source holders 104a and 104b, whichare standing in the installation chamber 103 (see FIG. 7C).

Further, a cleaning gas (one gas, or a plurality of gasses selected fromthe group consisting of H₂, F₂, NF₃, and O₂) introduction system may beprovided in the installation chamber 103 so as to clean components suchas the evaporation source holder and the shutter. It is also possiblethat plasma is generated by providing a plasma generating means in theinstallation chamber, or a gas that is ionized by plasma is introducedin the installation chamber such that components such as the inner wallof the installation chamber, the evaporation source holder, and theshutter are cleaned, and the interior of the installation chamber isvacuum-exhausted by use of the vacuum exhaust means. Plasma for cleaningthe aforementioned components may be generated by exciting one gas, or aplurality of gasses selected from the group consisting of Ar, N₂, H₂,F₂, NF₃, and O₂.

The film formation chamber can be kept clean by transporting theevaporation source holders 104 a and 104 b into the installation chamber103 and cleaning in the installation chamber 103.

Further, this embodiment can be freely combined with Embodiment Mode 2.Note that the evaporation device as depicted in FIG. 6 may be arrangedin any one of the film formation chambers 506W1, 506W2, and 506W3,whereas the installation chamber as depicted in FIGS. 7A and 7B may bearranged in any one of the installation chambers 526 a to 526 n asdepicted in FIG. 5.

Embodiment 4

Embodiment 4 will show an example of a film formation chamber in whichan interior of a film formation chamber and an evaporation mask can becleaned without being exposed to the atmospheric air. FIG. 8 is a crosssectional view sowing the film formation chamber of Embodiment 4.

As illustrated in FIG. 8, an example of generating a plasma 1301 betweenan evaporation mask 1302 a and an electrode 1302 b, which are connectedto each other via a high frequency power source 1300 a and a capacitor1300 b, will be described.

In FIG. 8, the evaporation mask 1302 a that is fixed in a holder isprovided in contact with a portion in which a substrate is formed (i.e.,a portion surrounded by a doted line). An evaporation source holder 1322that can heat at different temperatures is formed underneath theevaporation mask 1302 a. The evaporation source holder 1322 can be movedin a X direction, a Y direction, a Z direction, or a θ direction, whichis identical with a rotation direction.

The organic compound in the film formation chamber is heated up to asublimation temperature by heating means provided in the evaporationsource holder (typically, by resistive heating), and, hence, the organiccompound is vaporized and evaporated to a surface of the substrate. Whenvapor deposition is carried out, a substrate shutter 1320 is moved to aposition where the substrate shutter does not block the vapordeposition. Since the evaporation source holder is equipped with ashutter that move along the evaporation source holder, the shutter 1321is also moved to a position where the shutter 1321 does not block thevapor deposition, when the vapor deposition is carried out.

In vapor deposition, a gas introduction system, which enables to flow atrace amount of a gas formed of a smaller particle than a particle of anorganic compound material, i.e., a material having a smaller atomicradius so as to soak the organic compound film with the material havinga smaller atomic radius is provided. More specifically, one or aplurality of types of gases selected from the group consisting of asilane group gas (such as monosilane, disilane, and trisilane), SiF₄,GeH₄, GeF₄, SnH₄, and a hydrocarbon group gas (such as CH₄, C₂H₂, C₂H₄,and C₆H₆) may be used as the material gas having a smaller atomicradius. A mixed gas in which aforementioned gases are diluted byhydrogen or argon may also be used as the material gas having a smalleratomic radius. For these gases introduced into the device, gases highlypurified by a gas purifier prior to the introduction into the device areused. Therefore, it is required that a gas purifier is implemented sothat the gas is introduced into the evaporation device following thehigh purification of the gas. Since by utilizing this, remnant gas (suchas oxygen, moisture and the other impurities) contained in the gas canbe previously removed, which prevents the impurities from beingintroduced into the interior of the device.

For instance, if the light emitting element has defect portions such aspin holes and short circuits after the light emitting element iscompletely formed by adding Si, the defect portions is heated byintroducing monosilane gas in vapor deposition such that Si reacts andforms an insulator such as SiOx and SiCx, which reduces leakage in thepin holes and the short circuits. Therefore, point defects (dark spotsetc.) are not expanded, and hence, a self-healing effect can beobtained.

The components of the material gas introduced by heating substrate canbe efficiently deposited by using a heating means such as a heater 1304for heating a substrate.

Further, a radical may be generated by a plasma generating means. Forinstance, in case of using monosilane, a silicon oxide precursor such asSiHx, SiHxOy and SiOy is generated by the plasma generating means suchthat the generated silicon oxide precursor is deposited over thesubstrate along with the organic compound material from the evaporationsource. Monosilane easily reacts to oxygen, moisture and the like, andtherefore can reduce a oxygen content or a moisture content in the filmformation chamber.

Moreover, in order to introduce plural kinds of gases in the filmformation chamber, the vacuum exhaust processing chamber is equippedwith a magnetic levitated type turbo molecular pump 1326 and cryopump1327. By utilizing these pumps, an ultimate vacuum degree in thetransport chamber is allowed to be in the range of from 10⁻⁵ Pa to 10⁻⁶Pa. After the vacuum exhaust is carried out by use of the cryopump 1327,the cryopump 1327 is stopped, and the vacuum exhaust is furtherperformed by use of the turbo molecular pump 1326 while vapor depositionis carried out by flowing several sccm of the material gas. It is alsopossible that the material gas is ionized in the film formation chamberand is adhered to the evaporated organic material so as to carry outvapor deposition by the ion plating method.

After the termination of vapor deposition, the substrate is taken out,and then cleaning for removing the evaporation materials adhered to afixture provided in the film formation chamber and the inner wall of thefilm formation chamber is performed without being exposed to theatmospheric air.

The cleaning is preferably carried out by transforming the evaporationsource holder 1322 into the installation chamber (not illustrated here).

In the cleaning, the wiring electrode 1302 b is transported into theposition opposite to the evaporation mask 1302 a. Further, the gas isintroduced into the film formation chamber 1303. The gas to beintroduced into the film formation chamber 1303 may be one or aplurality of types of gases selected from the group consisting of Ar,H₂, F₂, NF₃, and O₂. Next, a high frequency electric field is applied tothe evaporation mask 1302 a from the high frequency power source 1300 ato excite the gas (Ar, H, F, NF₃, or O ) and generate plasma 1301. Insuch a manner, plasma 1301 is generated in the film formation chamber1303 and the evaporation substances adhering to the inner wall of thefilm formation chamber, the deposition preventing shield 1305, and thedeposition mask 1302 a are evaporated and exhausted outside of the filmformation chamber. By the film formation apparatus shown in FIG. 4,cleaning can be carried out at the time of maintenance without exposingthe interior of the film formation chamber and the evaporation mask tothe atmospheric air.

In this case, although the example in which plasma is generated betweenthe evaporation mask 1302 a and the electrode 1302 b interposed betweenthe evaporation mask 1302 a and the evaporation source holder 1306 isexemplified, the invention is not limited to that but include any aslong as it comprises a plasma generating means. Further, a highfrequency power source may be connected to the wiring electrode 1302 b.Further, a plate electrode, a mesh electrode or an electrode just like ashower head into which a gas can be introduced can be substitute for thewiring electrode 1302 b. Note that, as the plasma generating method,ECR, ICP, helicon, magnetron, second frequency, triode, LEP, and thelike can be arbitrarily utilized.

Further, the above-mentioned cleaning by means of plasma may be carriedout every film formation process and also may be carried out after thecompletion of multiple film formation processes.

This embodiment can be freely combined with Embodiment Mode 2 andEmbodiment 3.

Embodiment 5

In Embodiment 5, element characteristics of an organic light emittingelement (including a element constitution of: ITO/Cu-Pc (20 nm)/α-NPD(30 nm)/CBP+Pt(ppy)acac: 15 wt % (20 nm)/BCP (30 nm)/CaF (2 nm)/Al (100nm)) will be described. An emission spectrum of the organic lightemitting element having aforementioned constitution is depicted as aspectrum 1 in FIG. 10 and FIG. 11.

A spectrum in FIG. 10 denotes an emission spectrum in case of flowing 1mA of electric current in the organic light emitting element havingaforementioned constitution (at a luminance of about 960 cd/m²).According to the results as shown in the spectrum 1, it is confirmedthat white color light emission including following three components canbe obtained: blue color light emission (approximately 450 nm) of α-NPDcontained in the first light emitting layer; green color phosphorescence(approximately 490 nm) of Pt(ppy)acac contained in the second lightemitting layer; and orange color excimer emission (approximately 570 nm)of Pt(ppy)acac contained in the second light emitting layer. A CIEchromaticity coordinates of white color light emission are (x,y)=(0.346, 0.397). The luminance is almost white color, visually.

By measuring the ionization potentials of α-NPD used for the first lightemitting layer and CBP used for a host material of the second lightemitting layer, the ionized potential of α-NPD was approximately 5.3 eV,and that of CBP was approximately 5.9 eV. The difference betweenionization potentials of α-NPD and CBP was approximately 0.6 eV, andthis value meets the preferable condition of not less than 0.4 eVaccording to the present invention, which is supposed to result in afavorable white color light emission. Note that the ionizationpotentials are measured by using a photoelectron spectroscopy apparatus#AC-2 (manufactured by Riken Keiki Co., Ltd.).

FIG. 11 is a graph showing measured spectrums by changed values ofelectric current flowing in the organic light emitting element havingaforementioned constitution. The measurement results in case of changingthe electric current value according to “spectrum a” (0.1 mA), “spectrumb” (1 mA) and “spectrum c” (5 mA) are depicted in FIG. 11. As apparentfrom the results, if the electric current is increased (or if luminanceis increased), the shape of spectrum is hardly changed. Accordingly, itis known that the organic light emitting element of the presentembodiment exhibits stable white color light emission that is notadversely affected by the change of the electric current value. In FIG.11, light emission intensity of the whole spectra are normalizedaccording to each light intensity of a specific wavelength.

As electric characteristics of the organic light emitting element havingaforementioned constitution, a luminance of approximately 460 cd/m² wasobtained in case of setting the electric current density to 10 mA/cm².

Comparative Example 1

As compared with the case of Embodiment 5, emission spectra of theorganic light emitting elements, which are formed at concentrations ofPt(ppy)acac different from that of Embodiment 5 will be depicted as aspectrum 2 and spectrum 3 in FIG. 10. The spectrum 2 denotes themeasurement result when the concentration of Pt(ppy)acac is 7.9 wt %,whereas the spectrum 3 denotes the measurement result when theconcentration of Pt(ppy)acac is 2.5 wt %. In each case, 1 mA electriccurrent flows in each spectrum.

As shown in the spectrum 3, when the concentration of Pt(ppy)acac is 2.5wt %, only blue color light emission (approximately 450 nm) of α-NPDthat forms the first light emitting layer and green color light emission(approximately 490 nm and 530 nm) of Pt(ppy)acac contained in the secondlight emitting layer are observed. As result, white color light emissionis not obtained. Meanwhile, as shown in the spectrum 2, when theconcentration of Pt(ppy)acac is 7.5 wt %, excimer light emission ofPt(ppy)acac is slightly added to spectrum in the vicinity of 560 nm as ashoulder. However, the peak intensity is not enough to providesufficient white color light emission.

This embodiment can be freely combined with Embodiment Mode 1 andEmbodiment Mode 2.

According to the present invention, one sheet panel can providedual-sided emission display in which, for instance, different images canbe displayed (in full color display, monochrome display or area colordisplay) on a topside screen and a backside screen.

Furthermore, since the light emitting element emits white color light, ahigh-precision metal mask for selectively evaporating each regioncorresponding to R, G, and B is unnecessary, which increasingproductivity. In addition, when vapor deposition is selectively carriedout for each region corresponding to R, G, and B, a large number ofevaporation chambers must be provided for R, G, and B. On the otherhand, when the light emitting element emits white color light, thenumber of the evaporation chambers provided for the manufacturing devicecan be relatively reduced.

1. (canceled)
 2. A light emitting device comprising a pixel portion, thepixel portion comprising: a light emitting element comprising: a firsttransparent electrode; a second transparent electrode; and a lightemitting layer between the first and second transparent electrodes; anda color filter, wherein light emission from the light emitting layer andpassing through the first transparent electrode generates a full colordisplay on a first surface of the light emitting device by the colorfilter, and wherein light emission passing through the secondtransparent electrode generates a monochrome display on a second surfaceof the light emitting device.
 3. A light emitting device according toclaim 2, wherein the light emitting element is interposed between afirst polarizing plate and a second polarizing plate.
 4. A lightemitting device according to claim 3, wherein a polarizing axis of thefirst polarizing plate is perpendicular to a polarizing axis of thesecond polarizing plate.
 5. A light emitting device according to claim2, wherein the light emitting layer comprises an organic metal complex.6. A light emitting device according to claim 2, further comprising athin film transistor electrically connected to the first transparentelectrode.
 7. A light emitting device according to claim 2, wherein thelight emission is white color light emission.
 8. An electronic equipmentcomprising the light emitting device according to claim 2, wherein theelectronic device is one of a computer, a camera and a cellular phone.9. A light emitting device comprising a pixel portion, the pixel portioncomprising: a light emitting element comprising: a first transparentelectrode; a second transparent electrode; and a light emitting layerbetween the first and second transparent electrodes; a first colorfilter comprising: a red color layer; a green color layer; and a bluecolor layer; a second color filter comprising one of a red color layer,a green color layer and a blue color layer, wherein light emission fromthe light emitting layer and passing through the first transparentelectrode generates a full color display on a first surface of the lightemitting device by the first color filter, and wherein light emissionfrom the light emitting layer and passing through the second transparentelectrode generates a monochrome display on a second surface of thelight emitting device by the second color filter.
 10. A light emittingdevice according to claim 9, wherein the light emitting element isinterposed between a first polarizing plate and a second polarizingplate.
 11. A light emitting device according to claim 10, wherein apolarizing axis of the first polarizing plate is perpendicular to apolarizing axis of the second polarizing plate.
 12. A light emittingdevice according to claim 9, wherein the light emitting layer comprisesan organic metal complex.
 13. A light emitting device according to claim9, wherein the light emission is white color light emission.
 14. Anelectronic equipment comprising the light emitting device according toclaim 9, wherein the electronic device is one of a computer, a cameraand a cellular phone.